Grafting of organic compounds to the surface of glass products makes it possible to improve their characteristics or those of composite materials when these products are thereafter associated with another matrix. Thus, for example, it is well known that the mechanical, electrical and chemical properties of composite materials which have been reinforced with glass fibers are improved when there is an increased cohesion between the fibers and the matrix. One method for obtaining this strong cohesion is the use of fibers to which have been grafted unsaturated monomers able to react with the constituents of the matrix to be reinforced. A number or processes for grafting such monomers to glass fibers are already known but they all generally begin with a treatment of the fiber.
One such process involves subjecting the fiber to a flow of accelerated electrons, but this treatment does not always provide suitable results. When the fiber has previously been coated with a silane-based compound, it is believed that the radiation generates short-lived species or gives rise to free radicals that are not labile at the temperatures to which the fiber is subjected in the monomer solution. It has also been postulated that the accelerated electrons cause the bonds of the silane molecule to break at the level of the silicon atom, thus permitting a reaction with the grafting reagents.
An alternate process known in the prior art involves subjecting the fiber to the coupled action of water and temperature, then placing it in a vacuum to eliminate the oxygen and subsequently, contacting it with a solution or a mixture of monomers containing a catalyst. The catalyst, for example a peroxide, has the effect of triggering a homopolymerization or copolymerization reaction between the surface of the fiber and the polymer. One feature which limits the advantage of such a process is the length of time required for this process.
The discussion above relating to the treatment of glass fibers also applies to other glass products such as glass microballs or microspheres, glass packagings and glazings intended for buildings as well as for the automobile industry.